Embodiments of the invention relate to miniature fluidic devices, such as microfluidic devices, and more particularly, to fluidic connectors for introducing fluids in miniature fluidic devices.
Typically, microfluidic devices employ networks of chambers that are connected by microchannels. The microchannels and chambers may have meso-scale to micro-scale dimensions. Microfluidic devices, when used in analytical applications, offer various advantages, including the ability to use small sample sizes. For example, the sample sizes for the microfluidic devices may be on the order of nano-liters.
Advantageously, the microfluidic devices may be produced at a relatively low cost, and may perform numerous specific operations, including mixing, dispensing, reacting, and detecting. However, introducing fluid samples and reagents into the microfluidic devices is a challenge, especially when multiple inputs are required. For example, in a lab-on-a-chip setting, there is a need to connect the microfluidic chip to input and output interfaces. Connecting the microfluidic chip or connecting the microchannels within the chip to other input and/or output interfaces may pose problems due to small size (typically ranging from a few micrometers in width or diameter to tens or hundreds of micrometers) of the microchannels. In addition, it may be difficult to, for example, align input devices with the small-sized microchannels. Also, some of the input devices, e.g. liquid chromatographs, work at high pressures and it may be difficult to prevent leakage when using such input devices.
A common technique used in the past for interfacing the microfluidic devices to each other and to the outside world involves bonding a length of tubing of the input and/or output devices to a port on the microfluidic device. Usually, the tubing is bonded to the port on the microfluidic device using a suitable adhesive, such as epoxy. However, adhesive bonding is unsuitable for many chemical analysis applications because the solvents used in bonding may introduce impurities in the chemical sample. Further, the solvents used for bonding may attack the adhesive, which can lead to detachment of the tubing, channel clogging, and/or contamination of the sample and/or reagents delivered to the microfluidic device. Moreover, adhesive bonding, such as epoxy bonding, provides a permanent joint, thereby reducing the probability of having a reconfigurable device. For example, the permanent joint makes it difficult to change components, i.e., either the microfluidic device or the tubing, if necessary. Thus, assembly, repair and maintenance of such devices become labor and time intensive, a particularly undesirable feature when the microfluidic device is used for high throughput screening of samples such as, drug discovery, or in research environment, where reconfigurability of interfacing devices is useful.
To overcome problems associated with adhesive bonding, other techniques have been proposed in the past, e.g., press fitting the tubing into a port on the microfluidic device. However, such a connection typically is unsuitable for high-pressure applications such as high-pressure liquid chromatographs. Also, such connections have very low levels of tolerance. Particularly, the very low levels of tolerance pose a challenge in systems that employ multiple connectors for devices (i.e., scale up). Also, such connections require high sealing forces; these high sealing forces may sometimes cause the microfluidic chip to crack.
Other methods involve introducing liquids into an open port on the microfluidic device with the use of an external delivery system such as a pipette. In these methods, connection to the ports on the microfluidic device is typically by means of a micropipette end. However, this technique is also undesirable due to the possibility of leaks and spills that may lead to contamination. In addition, the fluid is delivered discretely rather than continuously. Moreover, the open pipetting techniques do not permit the use of elevated pressure for fluid delivery such as delivery by a pump, thereby further restricting the applicability of the microfluidic device.
Therefore, there exists a need for an improved fluid connector device for microfluidic devices, which is useful in different applications of the microfluidic devices and provides an effective, high pressure, low fluid dead volume seal.